package P3_11;

/**
A cash register totals up sales and computes change due.
*/
public class CashRegister
{
private double purchase;
private double payment;

/**
   Constructs a cash register with no money in it.
*/
public CashRegister()
{
   purchase = 0;
   payment = 0;
}

/**
   Records the sale of an item.
   @param amount the price of the item
*/
public void recordPurchase(double amount)
{
   double total = purchase + amount;
   purchase = total;
}

/**
   Enters the payment received from the customer.
   @param amount the amount of the payment
*/
public void enterPayment(double amount)
{
   payment = amount;
}

/**
   Computes the change due and resets the machine for the next customer.
   @return the change due to the customer
*/
public double giveChange()
{   
   double change = payment - purchase;
   purchase = 0;
   payment = 0;
   return change;
}

}
